OBJECTIVE: To analyze the time characteristics of the Ethos online adaptive radiotherapy (OART) process in clinical practice and provide guidance for the comprehensive optimization of each stage of adaptive radiotherapy. METHODS: The study involved 61 patients with cervical, rectal, gastric, lung, esophageal, and breast cancers who underwent Ethos OART. The mean ± standard deviation of segmental time, total time, and target volume for these patients were tracked. The time characteristics for different cancer types were evaluated, and the average time for target and organ at risk (OAR) modifications was compared with the average target volume for each cancer type. RESULTS: Cervical cancer born the longest total treatment time, while breast cancer had the shortest. For all cancer types except breast cancer, the modification time for target and OAR was the most time-consuming segment. The average time for target and OAR modifications aligned with the trend of the average target volume. CONCLUSION The total treatment time for various cancers ranges from 15 to 35 minutes, indicating room for improvement.
Humans ; Radiotherapy Planning, Computer-Assisted/methods* ; Neoplasms/radiotherapy* ; Female

Objective:To quantitatively analyze the differences in image quality and generated synthetic-computed tomography(sCT)between cone beam CT(CBCT)and iteration CBCT(iCBCT),which based on filtered back projection(FBP)and iterative reconstruction(IR)techniques of Varian Ethos adaption system.Methods:Using the special Catphan604 phantom of the test of CT image quality,five times of scanning series of CBCT and iCBCT were respectively performed based on thoracic and abdominal scanning protocols,so as to obtain four sets of images,and each set of image included the CBCT image,the composited sCT and iCBCT images based on CBCT,the composited sCT bases on iCBCT.The noise power spectrum(NPS),image uniformity(UI),modulation transfer function(MTF),low-contrast visibility(LCV)and contrast-to-noise ratio(CNR)of them were analyzed.Additionally,a retrospective analysis was conducted on images of six patients who underwent clinical radiotherapy,and the images of them were obtained by using thoracic and abdominal scanning protocols.The sCT images,which were generated by deformable registrations on the basis of CBCT and iCBCT,were analyzed,and they were compared with located CT images,and their mean absolute error(MAE)and root mean square error(RMSE)were further quantitatively analyzed.Results:Compared to CBCT,iCBCT significantly reduced NPS(thoracic images reduced by 0.08,abdominal images reduced by 0.06).The UI values of thoracic images and abdominal images of iCBCT were respectively 0.37 and 0.28,and those of CBCT were respectively 0.65 and 0.39.The LCV values of thoracic images and abdominal images of iCBCT were respectively 0.67 and 0.56,and those of CBCT were respectively 0.93 and 0.90.The MTF50％were 0.28 lp/mm except abdominal image of iCBCT was 0.29 lp/mm.The resolution rate of high contrast between iCBCT and CBCT was basic consistency.The differences of similarity analysis of the generated sCT and located CT bases on CBCT and iCBCT was no significant(P＞0.05).Conclusion:The image quality of iCBCT is superior to conventional CBCT.The accuracy of CT value of generated sCT bases on CBCT and iCBCT can meet requirement,and both of them can be used in the dose calculation of adaptive radiotherapy.